Package identifying transponders are used in supply chain logistics to track packages in the supply chain. A form of transponder increasingly being used is a radio frequency identification (RFID) tag which may be an active device or a passive device. The tag is attached to the package to be monitored and, generally, when interrogated by an interrogator, emits a response signal representative of the identity of the package to which the tag is attached.
It has been proposed to use RFID tags to monitor whether or not a package has been tampered with. With such an arrangement, the connection between the RFID chip and its antenna is broken when an attempt is made to gain unauthorized access to contents of the package so that, when the RFID tag is interrogated, there is no response to the interrogation signal. The lack of a response is meant to serve as an indication that tampering with the package has occurred.
There are two problems associated with such an arrangement. Firstly, it is a relatively simple procedure to re-establish the connection between the RFID chip and its antenna. Someone with nefarious intentions and who is aware of the arrangement could re-establish the connection so that, when the RFID tag is subsequently interrogated, it responds as it is supposed to.
Secondly, the connection between the RFID chip and its antenna may be broken for reasons other than tampering. An otherwise safe package may then be disposed of needlessly due to the failure to receive a response when interrogated.